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Individual diet specialization, niche width and population dynamics: implications for trophic polymorphisms
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2004 (English)In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 73, no 5, 973-982 p.Article in journal (Refereed) Published
Abstract [en]

1. We studied a perch Perca fluviatilis L. population that during a 9-year period switched between a phase of dominance of adult perch and a phase dominated by juvenile perch driven by cannibalism and intercohort competition. We investigated the effects of these population fluctuations on individual diet specialization and the mechanisms behind this specialization.

2. Due to cannibalism, the survival of young-of-the-year (YOY) perch was much lower when adult perch density was high than when adult perch density was low.

3. Both the individual niche breadth (if weighed for resource encounter) and the population niche breadth were highest when adult population density was high and, consequently, individual specialization was highest at high adult perch densities.

4. When adult perch density was low, the abundances of benthic invertebrate and YOY perch were high and dominated the diet of adult perch, whereas the density of zoo-plankton was low due to predation from YOY perch. At high perch densities, benthic invertebrate abundance was lower and zooplankton level was higher and some perch switched to feed on zooplankton.

5. Our results show that individual specialization may fluctuate with population density through feedback mechanisms via resource levels. Such fluctuations may have profound implications on the evolution of resource polymorphisms.

Place, publisher, year, edition, pages
Hoboken: Wiley-Blackwell, 2004. Vol. 73, no 5, 973-982 p.
Keyword [en]
competition, density dependence, interindividual variation, intrapopulation variation, niche breadth
National Category
Environmental Sciences Ecology Zoology
Identifiers
URN: urn:nbn:se:umu:diva-8044DOI: 10.1111/j.0021-8790.2004.00868.xISI: 000223375900016OAI: oai:DiVA.org:umu-8044DiVA: diva2:147715
Available from: 2008-01-14 Created: 2008-01-14 Last updated: 2017-05-18Bibliographically approved
In thesis
1. Ecology and Evolution of Adaptive Morphological Variation in Fish Populations
Open this publication in new window or tab >>Ecology and Evolution of Adaptive Morphological Variation in Fish Populations
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The work in this thesis deals with the ecology and evolution of adaptive individual variation. Ecologists have long used niche theory to describe the ecology of a species as a whole, treating conspecific individuals as ecological equivalent. During recent years, research about individual variation in diet and morphology has gained interest in adaptive radiations and ecological speciation. Such variation among individual niche use may have important conservation implications as well as ecological and evolutionary implications. However, up to date we know very little about the extension of this phenomenon in natural populations and the mechanisms behind it.

The results in this thesis show that the extension of individual diet specialization is widely spread throughout the animal kingdom. The variation in diet is mainly correlated to morphological variation but not always. Furthermore, this variation in diet and morphology among individuals could be both genetically determined and environmentally induced and it mainly comes from trade-offs in foraging efficiency between different prey types.

The results from a number of studies of perch also show that individual perch differ in morphology and diet depending on habitat, where littoral perch has a deeper body compared to pelagic perch. This difference in morphology corresponds to functional expectations and is related to foraging efficiency trade-offs between foraging in the littoral and pelagic zone of a lake. The variation in morphology in perch is mainly due to phenotypic plasticity but there are also small genetic differences between the littoral and pelagic perch. Two separate studies show that both predation and competition may be important mechanism for the variation in morphology and diet in perch.

In conclusion, the results in this thesis show that individual variation in diet and habitat choice is a common phenomenon with lots of ecological and evolutionary implications. However, there are many mechanisms involved in this phenomenon on which we are just about to start learning more about, and only further research in this area will give us the full insight.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2004. 35 p.
Keyword
Ecology, competition, functional morphology, individual specialization, inter-individual variation, intra-population variation, morphological variation, ontogeny, Perca fluviatilis, perch, phenotypic plasticity, predation, trade-offs, Ekologi
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-196 (URN)91-7305-583-2 (ISBN)
Public defence
2004-03-19, Stora Hörsalen, KBC, Umeå, 10:00
Opponent
Supervisors
Available from: 2004-02-11 Created: 2004-02-11 Last updated: 2017-05-18Bibliographically approved

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